This invention is directed to testing equipment which can subject wire ropes, cables, slings and the like to extremely high loads, namely, up to 3,000,000 lbs. In conventional testing equipment of the type to which this invention is directed, a pair of parallel laterally spaced rails are supported upon a test bed and are spanned by a carriage or yoke assembly to which is secured one end of a sling which is to be tested. Each rail is formed from a plurality of heavy/thick cross-sectioned metal beams or members which are welded end-to-end to each other. A pair of hydraulic cylinders are arranged one between each rail and another carriage or crosshead to which the other end of the sling is connected. When the hydraulic cylinders are progressively pressurized, the sling is progressively loaded in tension and appropriate strain gauges, digital readout meters, etc. are used during standardized testing up to a certain capacity or up to sling breakage.
When the sling is loaded in tension during testing the rails are loaded in compression, and when the sling breaks the compression load of the rails is instantaneously transformed into a tension load from the rebound or recoil effect. Therefore, such conventional rails, which can be 200' long, must be able to carry both compression and tension loads and resist deterioration/fracture/bending when under load and when there is an instantaneous reversal in loading from rail compression to rail tension upon the fracture of a sling or the like.
In the past rails of 200' or longer that can carry compression or tension loads were made by making a 100% weld at the butt joints between the individual thick cross-sectioned metal beams or members. The problem with rails manufactured by butt-welding metal rail members to each other are at least twofold, namely, keeping the overall rail straight during and after welding because of the tremendous heat which will cause the metal rail members to warp and the high cost involved in the materials and the welding process. It is absolutely critical that the rails are straight, and if the individual rail members are warped or misaligned because of the welds, either coaxially relative to each other or relative to the rail arranged parallel thereto, the test load cannot be properly distributed, applied to the sling and/or absorbed under breakage and recoil.